Process of making a lead-alkali-metal alloy



Patented Sept. 23, 1924. I

innate? FEW Fifi

PATENT WILLi'AM S. CA LCOTT, F PENNSGROVE, NEW JERSEY, ASSIGNOR TO E. I. DU PONT DE NEMOURS do COMPANY, OF WILMINGTON, DELAWARE, A CORPORATION OF DELA- WARE.

PROCESS OF MAKING A LEAD-ALKALI-METAL ALLOY.

1T0 Drawing.

T 0 all whom it may concern:

Be it known that I, WILLIAM S.CALco'rr, a citizen of the United States, and a resident of Pennsgrove, in the county of Salem 5 and State of New Jerse haveinvented a certain new and useful rocess of Making a Lead-Alkali-Metal Alloy, of which the following is a specification.

This invention relates to a process of IOmaking an alloy of lead and sodium, and comprises heating together sodium and lead to form a homogeneous molten mass while preventing reactive gas, such as air, from coming in-contact: with the lead or sodium 1 by maintaining over the upper surface of said mass -a. liquid layer or film of a material which will not contaminate the alloy, and whose melting point is substantially lower than that of said alloy.

The composition of the particular alloy with which my invention is chiefly concerned corresponds to the formula PbNa The melting. point of this alloy is about' The mater-a1 which I have found to be especially advantageous for use as a protective layer for the molten lead-sodium al- 10y, is a mixture of sodium hydroxide and potassium hydroxide, and preferably the I eutectic mixture, that is 60% caustic potash and 40% caustic soda.

invention may be illustrated in greater detail by the following example:

' In a crucible provided with a carbon dioxide (CO inlet and supply are placed 13 parts of lead and 3 parts of sodium. The

airis then swept out with a current of CO and heat applied. When the temperature of the sodium reaches l50 0., the lead e0 gins to dissolve with a vigorous evolutlon of heat. When the temperature reaches- 200 C., 10 parts of mixed caustic (60% KOH, NaOH) are added. The sod-v ium by this time has dissolved sufiicient lead so that the density is greater than that of the caustic, which consequently floats on the surface and protects the alloy from oxidation. The mass is then maintained in a molten condition until it has become homogeneous. As the melting point of the mixed caustic is onl alloy is 400 (1., the caustic serves as an efficient protective layer till long after the al- 175 0., while that of the Application filed October 23, 1922. Serial No. 596,517.

loy has become solid, in which state it is relatively non-reactive.

The layer of caustic may be removed by pouring it off in the molten condition after the alloy hasflc'ooled sufficiently to solidify.

Although I prefer to usethe eutectic mix? ture of the hydroxides of sodium and potas'sium, it will be understood that various other mixtures may be used without departing from my invention,

The procedure described above may also be used in the manufacture of alloys of lead andsome other alkali-metal such as potasslum.

I claim: 1. The

rocess of making an alloy of lead and an a kali-metal, which comprises heat- -mg the two metals together to form a moltenimass, and excluding oxygen therefrom by maintaining over the upper surface of the molten alloy a liquid layer of a substance which will not contaminate said alloy, and which has a boiling point above, and a. melting point substantially below, thetemperature of said molten alloy.

2. A process of the kind set forth in claim 1 in which the liquid layer comprises a mixture of the hydroxides of sodium and potassium. t

3. A process of the kind set forth in claim 1 inwhich the li uid layer comprises the eutectic mixture 0 the hydroxides of sod ium' and potassium.

4. The process of making an alloy of lead and sodium, which comprises heating the two metals together with exclusion of oxygen to form a molten mass, and continuing to exclude oxygen therefrom by maintaining over the upper surface of the molten alloy a liquid layer of a substance which will not contaminate said alloy, and which has a boiling oint above, and a melting oint substiantlally below, the temperature 0 said molten alloy. a

5. A process of the kind set forth in claim 4 in which the liquid layer comprises a mixture of the hydroxides of sodium and potassium.

6. A ocess of the kind set forth in claim- 4 in w ich the liquid layer comprises the eutectic mixture of the hydroxides of sodium and potassium. 7. The process of making a lead-sodium alloy of approximately the composition perature of the mass until a homogeneous PbNa which comprises heating 130 parts molten alloy is formed with a layer of the 10 of lead with about 30 parts of sodium in an molten caustic mixture covering the alloy, atmosphere of carbon dioxide until the mass and then allowing the molten alloy to solidhas a temperature of about 200 C., then ify before removing the caustic mixture. adding a mixture comprising essentially 6 In testimony whereof I aflix my signature. parts of potassium hydroxide and 4 parts of sodium hydroxide, increasing the tem- WILLIAM S. CALCOTT. 

